GENTROPYXIS ACULEATA. 390 
ve 
Enetanp.—Isle of Man; Westmorland! (Brown) ; 
N. Yorkshire; Derbyshire (Brown) ; Bedfordshire. 
Wates.—North Wales. 
Scoti.anp.—Outer Hebrides ; Dumfries. 
Iretand.—Donegal; Clare Island and em 
Mayo; Kerry. 
The brown chitinous tests with 2 to 4 spines are 
perhaps less common in. Britain than the grey silicious 
ones; the latter are very rarely provided with spines. 
In Gormire Lake, Yorks, these are numerous, whilst in 
the sphagnum swamp at Pilmoor, Yorks, the brown 
tests are found. The spines when present ure never 
placed far apart, being distributed over one-third or 
less of the periphery. 
Living animals are, very scarce and active ones are 
hardly ever seen. 
2. Centropyxis arcelloides Penard. 
(Plate LXI, figs. 3 and 4.) 
Centropyxis arcelloides 
PrenaRD Faune Rhiz. Léman (1902), pp. 309-310, 4 figs.; Sarcodinés 
in Cat. Invert. Suisse (1905), p. 60. 
Waites & PenarD in Proc. R. Irish Acad. XXXI, txv (1911), 
pp. 9. 15. 
Waites in Jrn. Linn. Soc., Zoe XXXII (1912), p. 156; (1913), 
p. 212. 
Epmonpson in Ward & Whittle’ s Fresh-water Biology (1918),p. 221, 
f. 286. 
Test of medium size, usually brown in colour, 
hemispherical with rounded basal angle, composed of 
a chitinous membrane covered with small silicious 
plates; aperture large, placed. centrally in the base, 
slightly invaginated; plasma grey, granular; nucleus 
large, spherical, containing numerous minute nucleoles ; 
numerous vacuoles usually present; pseudopodia not 
observed. 
Diameter 80-110p; height about three-fifths the 
diameter ; aperture about half the diameter. 
Halitat—Mosses and sphagnum. 
8% 
